package com.teamwings.util;

import org.apache.shiro.codec.Base64;

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

/**
 * 加解密工具
 */
public class EncryptUtil {
	/**
	 * 使用AES-128-CBC加密模式，key需要为16位,key和iv可以相同！
	 * 长度为16个字符
	 */
	private final static String KEY = "1234567890adbcde";
	private final static String IV = "1234567890hjlkew";

	public static String getKey() {
		return KEY;
	}

	public static String getIv() {
		return IV;
	}

	/**
	 * 加密方法
	 * @param data  要加密的数据
	 * @param key 加密key
	 * @param iv 加密iv
	 * @return 加密的结果
	 * @throws Exception -
	 */
	public static String encrypt(String data, String key, String iv) throws Exception {
		try {
			Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding");//"算法/模式/补码方式"NoPadding PkcsPadding
			int blockSize = cipher.getBlockSize();

			byte[] dataBytes = data.getBytes();
			int plaintextLength = dataBytes.length;
			if (plaintextLength % blockSize != 0) {
				plaintextLength = plaintextLength + (blockSize - (plaintextLength % blockSize));
			}

			byte[] plaintext = new byte[plaintextLength];
			System.arraycopy(dataBytes, 0, plaintext, 0, dataBytes.length);

			SecretKeySpec keyspec = new SecretKeySpec(key.getBytes(), "AES");
			IvParameterSpec ivspec = new IvParameterSpec(iv.getBytes());

			cipher.init(Cipher.ENCRYPT_MODE, keyspec, ivspec);
			byte[] encrypted = cipher.doFinal(plaintext);

			return Base64.encodeToString(encrypted);

		} catch (Exception e) {
			e.printStackTrace();
			return null;
		}
	}

	/**
	 * 解密方法
	 * @param data 要解密的数据
	 * @param key  解密key
	 * @param iv 解密iv
	 * @return 解密的结果
	 * @throws Exception -
	 */
	public static String desEncrypt(String data, String key, String iv) throws Exception {
		try {
			byte[] encrypted1 = Base64.decode(data);

			Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding");
			SecretKeySpec keyspec = new SecretKeySpec(key.getBytes(), "AES");
			IvParameterSpec ivspec = new IvParameterSpec(iv.getBytes());

			cipher.init(Cipher.DECRYPT_MODE, keyspec, ivspec);

			byte[] original = cipher.doFinal(encrypted1);
			return toStr(original).trim();
		} catch (Exception e) {
			e.printStackTrace();
			return null;
		}
	}

	/**
	 * 去除补0（如果加密的原数据长度很短，加密时会自动在后面补0，因此在解密后转字符串时必须把后面的0去掉）
	 * @param buffer -
	 * @return -
	 */
	private static String toStr(byte[] buffer) {
		try {
			int length = 0;
			for (int i = 0; i < buffer.length; ++i) {
				if (buffer[i] == 0) {
					length = i;
					break;
				}
			}
			if (length == 0) {
				length = buffer.length;
			}
			return new String(buffer, 0, length);
		} catch (Exception e) {
			e.printStackTrace();
			return "";
		}
	}

	/**
	 * 使用默认的key和iv加密
	 * @param data -
	 * @return -
	 * @throws Exception -
	 */
	public static String encrypt(String data) throws Exception {
		return encrypt(data, KEY, IV);
	}

	/**
	 * 使用默认的key和iv解密
	 * @param data -
	 * @return -
	 * @throws Exception -
	 */
	public static String desEncrypt(String data) throws Exception {
		return desEncrypt(data, KEY, IV);
	}
}
